The present invention relates generally to condition monitoring systems and, more particularly, to a system that monitors air pressure in the tires of a motor vehicle trailer, and that generates a visual signal viewable by a vehicle occupant indicative of the tire pressure in each of the tires to improve tire life, minimize tire wear, and increase vehicle performance and safety.
Correct tire pressure is a critical factor in the safe operation and performance of a motor vehicle. Over inflated tires often result in unnecessary tire wear and less than optimal vehicle performance. Under inflated tires typically result in increased tire wear, decreased vehicle performance, and compromise the ability of the tires to maintain a safe interface with the road.
Conventionally, tire air pressure has been checked with mechanical gauges designed to be inserted over tire inner tube valve stems. Such gauges provide a generally accurate air pressure reading. However, the gauges are incapable of providing continuous monitoring of the air pressure within the tires and are limited in accuracy, and also require a driver concerned about tire air pressure to physically stop and exit the vehicle to check the tire pressure. In addition, such mechanical gauges do not provide any warning indication when the tire pressure reaches a level considered to be dangerous or unsuitable (such as below 14 psi in a typical passenger motor vehicle) for normal driving conditions.
Other systems utilize an active inductor capacitor (LC) circuit affixed within the tire to monitor tire air pressure. However, active LC circuits require a power source for operation. Because it is mounted within the tire, the power source, as well as the additional circuit components, are subjected to rotational vibration and other extreme conditions caused by temperature fluctuation. The circuit components may also be difficult to install and replace if damaged or depleted due to their location within the tire. In addition, such systems typically provide no warning to the driver when the tire pressure falls below or rise above a certain minimum/maximum acceptable level. Moreover, these active inductor capacitor (LC) type systems generally also utilize battery power when the vehicle is both in operation and also in a parked non-use condition, thereby reducing the overall battery life of the active inductor capacitor (LC) circuit.
Other systems may utilize a sensor system that require the location of the sensor relative to a receiver pickup to be in very close proximity to one another. This provides a great disadvantage in enabling various options for mounting locations of the receiver relative to the sensor which may invariably lead to mounting the receiver in a very harsh environment location. Additionally, such systems may also require very large size inductors (L) which is also very difficult and, in some instances, not practical for mounting within vehicle tires. These types of systems may also increase the overall undamped weight of the overall tire by requiring such a large inductor (L). Other systems also require hard wiring of pickup receivers to indicator devices in the vehicle. This type of hard wiring must be, thereby routed throughout the vehicle wiring system either during production of the vehicle or for after-market use. This makes it very difficult to install such a system for aftermarket use since generally this wiring must be mounted throughout the vehicle. Other systems further do not provide diagnostics to identify whether or not the system is, in fact, working properly.
Most tire pressure sensing systems are also primarily directed to sensing vehicle tire pressure. However, monitoring tire pressure of trailers attached to a vehicle is also a desired feature. When monitoring the tire pressure of a tire mounted on a trailer, however, in most instances the vehicle will require an indicator module and additional wiring mounted and located within the vehicle itself. This makes it difficult to retrofit a vehicle when a trailer is used. Also, drivers may not want to have associated accessories mounted within their vehicle when they only utilize a trailer on a part time basis. There is, therefore, a need for a tire sensor monitoring system which can easily and efficiently monitor tire pressure in a tire that is mounted on a trailer without requiring any modifications to the tow vehicle itself.
What is needed then is a tire pressure sensing system which does not suffer from the above-mentioned disadvantages. This, in turn, will provide a sensing system which monitors tire air pressure using an active sensor, that conserves battery life, provides improved mounting of the sensor within the tire, provides a system which is less susceptible to interference, provides a sensor system which can accurately monitor the change in tire air pressure, provides improved sensors which operate to identify if the tire air pressure is outside a pre-determined range, provide a sensor system which enables more versatility in the placement of a pickup receiver, provide a sensor system which conserves sensor battery power when the vehicle is not in use, provide a sensor system which can easily be installed for aftermarket use without requiring hard wiring between a receiver pickup and an indicator device, and provide system diagnostics to confirm proper operation of the overall tire monitoring system. It is, therefore, an object of the present invention to provide such a tire pressure sensing system.
The present invention provides a tire pressure monitoring system that utilizes an active LC circuit mounted within the tire of a trailer for monitoring tire air pressure. The active circuit conserves battery power by stabling the circuit when the vehicle is not in use. The tire pressure monitoring system of the present invention is configured to provide a visual indication to the driver when tire pressure in any of the tires on the trailer falls below a minimum acceptable level.
Use of the present invention provides a tire pressure monitoring system for monitoring air pressure within a tire on a trailer. The present invention further provides a system for monitoring a first parameter with a sensor located at a first location and a receiver located at a second location. As a result, the aforementioned disadvantages associated with the currently available methods and techniques for monitoring tire air pressure have been substantially reduced or eliminated.